Photovoltaic devices are known in the art (e.g., see U.S. Pat. Nos. 6,784,361, 6,288,325, 6,613,603, and 6,123,824, the disclosures of which are hereby incorporated herein by reference). Some conventional mainstream photovoltaic modules use a large number of crystalline silicon (c-Si) wafers. The inclusion of the large number of c-Si wafers tends to dominate the cost of the overall photovoltaic module. Indeed, about 60% of the costs involved in the production of conventional photovoltaic modules is related to the c-Si solar cells. To address this issue, concentrated photovoltaic (CPV) systems have been proposed, in which the sunlight is to be focused with concentration ratios of 100× to 1000×. Calculations suggest that a concentration ratio of approximately 10× should enable a photovoltaic system to be produced that uses at least 90% less silicon material.
Unfortunately, however, current concentrated photovoltaic systems use expensive high efficiency multi-junction solar cells, expensive dual-axis tracking systems, and/or relatively expensive concentrating optics. Therefore, these systems have difficulty competing with other photovoltaic solutions on a cost per watt basis.
Thus, it will be appreciated there is a need in the art for a simple low-cost CPV systems, together with low cost solar cells and low-cost concentrating optics, and/or methods of making the same.
One aspect of certain example embodiments relates to a patterned glass cylindrical lens array, and/or methods of making the same.
Another aspect of certain example embodiments relates to using such a cylindrical lens array to focus light on substantially elongate or strip solar cells.
Another aspect of certain example embodiments relates to lateral displacement tracking systems, and/or methods of making and/or using the same.
Further aspects of certain example embodiments relate to building-integrated photovoltaic systems, which may include insulating glass units comprising cylindrical lens arrays and strip solar cells. In certain examples, the photovoltaic system may be integrated into a building as an insulated glass skylight.
According to certain example embodiments, lateral tracking of a solar cell strip substrate relative to a lenticular array that concentrates light thereon advantageously results in cost-effective electricity generation, self-regulated solar heat gain control, and diffuse daylight entry, thereby providing a multifunctional BIPV product. The concentration ratio preferably is at least 2:1, more preferably at least about 3:1, although high concentration ratios are possible. In some instances, heat sinks may be provided to keep the assembly cool, e.g., when high concentration ratios are provided.
According to certain example embodiments, the lens array does not move at all, but the PV array glass moves laterally to keep direct sunlight focused on the solar cell strips.
In certain example embodiments of this invention, a method of making a lens array for use in a solar photovoltaic module is provided. Glass is made using a float process or other process. The glass is patterned using a plurality of rollers disposed (e.g., potentially along the float glass) line so as to form a plurality of first lenses oriented along a common axis. The rollers each have profiles such that each said first lens is patterned to have at least one convex major surface when viewed in side cross section.
In certain example embodiments of this invention, a method of making a solar photovoltaic module is provided. A lens array comprising a plurality of lenses oriented along a common axis is provided, with the lenses being patterned using rollers (e.g., potentially along the float glass), and with the lenses each having at least one convex major surface when viewed in side cross section. A plurality of elongate solar cells is provided, with each said solar cell comprising c-Si. The lens array is oriented relative to the solar cells such that each said lens is arranged to concentrate light incident thereon in substantially one dimension on the elongate solar cells. In certain example instances, a solar photovoltaic module is made in this way, and the photovoltaic module may be operated by connecting it to a single-axis tracking system at a fixed tilt, with the single-axis tracking system being movable so as to match the East-West movement of the sun. However, in certain example embodiments, the PV array substrate and lens array may be spatially separated from each other and the PV array moves laterally to maintain focus of the sunlight on the PV strip cells during the course of the day.
In certain example embodiments of this invention, a method of making a solar photovoltaic system is provided. At least one lens array comprising a plurality of lenses oriented along a common axis is provided, with the lenses being patterned using rollers, and with the lenses each having at least one convex major surface when viewed in side cross section. The at least one lens array is oriented relative to a plurality of elongate solar cells comprising c-Si such that each said lens is arranged to concentrate light incident thereon in substantially one dimension on the elongate solar cells.
In certain example embodiments of this invention, a photovoltaic system is provided. A plurality of elongate solar cells is provided, with each said solar cell comprising c-Si. A lens array comprising a plurality of lenses oriented along a common axis is provided, with each said lens being configured to concentrate incident light in substantially one dimension the elongate solar cells, and with each said lens having a concentration ratio of 3×-30×.
In certain example embodiments of this invention, a building product is provided. A plurality of elongate solar cells comprising c-Si is supported by a cover glass substrate. A lens array comprises a plurality of lenses oriented along a common axis, with each said lens being configured to concentrate incident light in substantially one dimension on the elongate solar cells, and with the lens array being substantially parallel to and spaced apart from the cover glass substrate. Each said lens has a convex top and/or bottom surface when viewed in side cross section. The lens array is patterned from a single low-iron glass substrate. In certain example instances, a frame may be structured to maintain the lens array and the cover glass substrate in parallel spaced apart relation.
In certain cases, some example existing photovoltaic and building-integrated photovoltaic (BIPV) systems may focus primarily on electricity generations. In certain example embodiments of this invention, however, a BIPV system may be multi-functional in that it provides not only cost-effective electricity generation, but also other advantageous features such as daylight entry, variable solar control, thermal insulation, and/or an aesthetic building “skin.”
In certain example embodiments, the BIPV system may include a photovoltaic skylight. In some cases, the photovoltaic skylight may comprise an insulated glass unit (IGU).
In certain example embodiments, a BIPV system (e.g., photovoltaic skylight) may be provided on the roof of a building and/or other suitable structure. In certain example instances, the photovoltaic skylight may be installed on a roof at latitude tilts and may transmit diffuse daylight into the interior of the building, while converting direct sunlight into electricity at a relatively high efficiency.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.